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Astronomy

Webb telescope reaches L2 orbit

The Webb Space Telescope completed its final heading correction and entered the orbit of the second Lagrange Point (L2), which is about 1.5 million kilometers from Earth, at 2 p.m. eastern time on January 24, NASA reported. At present, the primary mirror and secondary mirror of the Webb telescope have been completed. After the telescope enters the L2 point orbit, engineers will begin a three-month complex debugging process to adjust the optical system of the telescope to a precision close to nanometer. The Webb telescope is expected to take the first image of the universe this summer.

Health

Nicotine intake during pregnancy can affect the sleep of offspring in adulthood

Recently, in a study published in the journal Science report, researchers used mouse models to find that fetal prenatal exposure to nicotine and its metabolic products can have long-term effects on sleep and stress responses in some areas of the brain in adulthood.

The researchers fed water containing nicotine and cotinine, the main product of nicotine metabolism in the body, to pregnant mice and found that it took longer for their offspring to transition from sleep to wakefulness in adulthood. The researchers also found that the expression of glucocorticoid receptors in the hippocampus of these offspring also changed. The hippocampus is very sensitive to stress factors during brain development and has many corticosteroid receptors. The researchers say the data show that changes in sleep patterns and the expression of glucocorticoid receptors occur simultaneously, suggesting that nicotine intake during pregnancy can affect the development of the hippocampus of offspring and affect their sleep patterns in adulthood.

Biology

New research questions the importance of meat in human evolution

Typical human characteristics first appeared in Homo erectus about 2 million years ago, such as their brain capacity is significantly larger than that of Australopithecus and can make stone tools. Some studies suggest that the evolution of these characteristics is related to meat. However, a new study published yesterday in the Proceedings of the National Academy of Sciences questions this hypothesis.

The researchers compiled published data from nine major research regions in eastern Africa, including 59 sites between 2.6 million and 1.2 million years ago, and tracked evidence of ancient human carnivore by analyzing animal bones with stone cutting marks. The results show that after the appearance of Homo erectus, although the number of animal bones with cutting marks in each site and the total number of archaeological sites containing such bones increased significantly, the increasing trend was closely related to the sampling frequency. When the sampling intensity of each stratum is adjusted to a unified level, the relative amount of carnivorous evidence does not increase. The researchers say the increase in such evidence is largely due to excessive attention to this period, probably due to intensive sampling rather than changes in Homo erectus behaviour, skewing the evidence to support the hypothesis that meat makes humans.

Zoology

Hippopotamus can recognize the voices of relatives, friends and strangers.

Hippopotamus roars can spread over long distances, which makes scientists suspect that hippopotamus has certain social functions. Recently, in a study published in Modern Biology, scientists recorded the characteristic calls of several hippopotamus populations in the Maputo special reserve in Mozambique and observed their different reactions to the recording of calls from themselves, neighbors (living in the same lake area) and strange ethnic groups.

The study found that hippopotamus responded differently, such as answering, approaching or spraying feces, after hearing the cries of different ethnic groups. When hearing the cry of a strange hippopotamus, hippopotamus are more likely to protect their territory by spraying faeces; they are less hostile to their neighbors. The findings provide implications for measures to protect hippopotamus: when a habitat is overcrowded, some hippopotamus populations can be moved elsewhere and their calls can be played in advance to familiarize new groups with "aborigines" and reduce hostility.

Physics

Global search for dark matter

Ultra-light boson is one of the particles most closely related to the study of dark matter. In theory, the specific distribution pattern of boson field can make dark matter gather in many discrete domain walls that are smaller than galaxies and larger than Earth. Recently, a study published in Nature Physics released for the first time comprehensive data on dark matter detection in conjunction with a global optical magnetometer network.

GNOME (the Global Network of Optical Magnetometers for Strange Physics search) involves eight countries and includes 14 magnetometers. The dark matter can disturb the nuclear spin in the magnetometer. When the dark matter domain wall passes through the earth, the magnetometer of the GNOME network will detect the transient characteristic signal, which is related to the speed of the domain wall moving and the time passing through each place. The team tried to analyze the data for a month and found no statistically significant signals in the range of 10-15 electron volts to 10-10 electron volts, narrowing the scope of future research. The researchers will update the magnetometer and data analysis, such as the use of inert gas in the magnetometer to make it more stable and sensitive. Dark matter detection based on GNOME propulsion will enhance the understanding of celestial motion and cosmic background radiation.

Zoology

Chimpanzees may learn to use tools through social learning.

Humans learn to use tools and other skills by observing each other. Through this form of social learning, human culture becomes more and more complex. However, there has been a debate about whether this way of accumulating culture is unique to human beings. In a new study published in the journal Natural Human behavior, researchers found that wild chimpanzees do not easily learn to use tools on their own, which may mean that such behaviors are acquired through social learning.

The researchers conducted a long-term field experiment in which they provided stone tools and nuts to a wild chimpanzee population in Guinea and its neighboring populations and used infrared cameras to photograph the results. They found that chimpanzees were initially interested in tools, but did not use them to open nuts and gradually lost interest over the months. But another isolated population of chimpanzees used tools to open nuts. Chimpanzees opening nuts is considered to be a cultural sexual behavior, which is only practiced in certain chimpanzee populations. These experiments show that even with tools, other chimpanzees cannot easily acquire this part of chimpanzee culture. The author believes that the culture of chimpanzees is very similar to human culture and may also be developed from members of social groups.